As to the cap, Jay, your guess is as good as mine (it's a bit better, in
truth).
The filters are not drop-in, but screw-on, assuming that your model is like
mine, with the filters mounted inside the lens. Quoting the instruction
sheet, it is "designed to give optimum results when used with a filter.
Please do not try to use the lens without any of the filters". I don't see
any refrence to infinity focus there, but I do see a reference to one
filter, not two.
I haven't heard about not using the lens on a 4T before. The mount has
three screws, unlike the "bad" Adaptall, and the problem screw seems to be
well away from the danger zone. Could it be that the circular image leaves
large parts of the frame unilluminated, causing exposure metering problems
if you do not use spotmetering? Certainly, it would be hard to use the lens
on an OM1 or OM2, beauce visibility of the meter needle would be seriously
affected - but that is true of the Zuiko 8mm too.
--
Piers
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
Of Jay Drew
Sent: 18 May 2007 02:47
To: Zuikoholic
Subject: [OM] Sigma 8mm Fisheye Questions
In a moment of madness I acquired a Sigma 8mm F4 fisheye filtermatic lens.
Naturally it does not have a manual. So for those that have had one in the
past I have a few questions:
1. The lens cap is in two pieces. One piece reduces the circular image to a
smaller circle. I've got a 16mm Sigma that has the same type of cap. For
the 16mm I understand that this split cap's purpose was to create a circular
image (pseudo fisheye) of the rectilinear image of the 16mm lens. What
purpose does this provide on the 8mm which is already circular? Is it to
provide circular cropping to reduce problems at the edges?
2. No additional filters were provided. There is a filter labeled "normal"
that is in place. My understanding is that the other filters are 22.5 mm
drop-in.
Eyeballing the "normal" filter I see female threads. So do the "drop in"
filters drop in or do the screw onto the back of the "normal" filter or do
they replace it. I had read that if the clear filter was not in place the
lens would not reach infinity focus correctly. Are the only filters that
fit the Sigma for the 8mm and 16mm? I've seen a spot were there were drop
in filters for a Sigma 600mm labeled as 22.5, just wondering if they would
work.
Finally, searching through the archives I found a post stating that the lens
did not work with a 4T. After eyeballing the mount to see if it would shave
off the reset button I put this on my OM4 and shot one frame without a
mirror hang (which is what I feared was the incompatibility). I'll steel my
nerves and put this on my 4T and try that. Anyone know why it shouldn't
work with a 4T? The meter does couple and that coupled with the spot
metering would be the ticket for getting correct exposure as opposed to
requiring the use of an external meter.
Jay - if you can't handle the truth, distort it with a fisheye.
Hand me my costume
Please won't you pass me my mask
I have appointments I must keep with my past.
Bill Nelson - Beauty Secrets
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